Expand DeprecatedLogWarn to check for Expr::Atrribute calls (#7677)

## Summary

`PGH002`, which checks for use of deprecated `logging.warn` calls, did
not check for calls made on the attribute `warn` yet. Since
#7521 we check both cases for
similar rules wherever possible. To be consistent this PR expands PGH002
to do the same.

## Test Plan

Expanded existing fixtures with `logger.warn()` calls

## Issue links

Fixes final inconsistency mentioned in
#7502

crates/ruff_linter/resources/test/fixtures/pygrep_hooks/PGH002_0.py

@@ -5,3 +5,6 @@
 warnings.warn("this is ok")
 warn("by itself is also ok")
 logging.warning("this is fine")
+
+logger = logging.getLogger(__name__)
+logger.warning("this is fine")

crates/ruff_linter/resources/test/fixtures/pygrep_hooks/PGH002_1.py

@@ -3,3 +3,6 @@
 
 logging.warn("this is not ok")
 warn("not ok")
+
+logger = logging.getLogger(__name__)
+logger.warn("this is not ok")

crates/ruff_linter/src/checkers/ast/analyze/expression.rs

@@ -746,7 +746,7 @@ pub(crate) fn expression(expr: &Expr, checker: &mut Checker) {
                 pygrep_hooks::rules::no_eval(checker, func);
             }
             if checker.enabled(Rule::DeprecatedLogWarn) {
-                pygrep_hooks::rules::deprecated_log_warn(checker, func);
+                pygrep_hooks::rules::deprecated_log_warn(checker, call);
             }
             if checker.enabled(Rule::UnnecessaryDirectLambdaCall) {
                 pylint::rules::unnecessary_direct_lambda_call(checker, expr, func);

crates/ruff_linter/src/rules/pygrep_hooks/rules/deprecated_log_warn.rs

@@ -1,7 +1,9 @@
-use ruff_python_ast::Expr;
+use ruff_python_ast::{self as ast, Expr, ExprCall};
+use ruff_python_semantic::analyze::logging;
 
 use ruff_diagnostics::{Diagnostic, Violation};
 use ruff_macros::{derive_message_formats, violation};
+use ruff_python_stdlib::logging::LoggingLevel;
 use ruff_text_size::Ranged;
 
 use crate::checkers::ast::Checker;
@@ -43,14 +45,36 @@ impl Violation for DeprecatedLogWarn {
 }
 
 /// PGH002
-pub(crate) fn deprecated_log_warn(checker: &mut Checker, func: &Expr) {
-    if checker
-        .semantic()
-        .resolve_call_path(func)
-        .is_some_and(|call_path| matches!(call_path.as_slice(), ["logging", "warn"]))
-    {
-        checker
-            .diagnostics
-            .push(Diagnostic::new(DeprecatedLogWarn, func.range()));
+pub(crate) fn deprecated_log_warn(checker: &mut Checker, call: &ExprCall) {
+    match call.func.as_ref() {
+        Expr::Attribute(ast::ExprAttribute { attr, .. }) => {
+            if !logging::is_logger_candidate(
+                &call.func,
+                checker.semantic(),
+                &checker.settings.logger_objects,
+            ) {
+                return;
+            }
+            if !matches!(
+                LoggingLevel::from_attribute(attr.as_str()),
+                Some(LoggingLevel::Warn)
+            ) {
+                return;
+            }
+        }
+        Expr::Name(_) => {
+            if !checker
+                .semantic()
+                .resolve_call_path(call.func.as_ref())
+                .is_some_and(|call_path| matches!(call_path.as_slice(), ["logging", "warn"]))
+            {
+                return;
+            }
+        }
+        _ => return,
     }
+
+    checker
+        .diagnostics
+        .push(Diagnostic::new(DeprecatedLogWarn, call.func.range()));
 }

crates/ruff_linter/src/rules/pygrep_hooks/snapshots/ruff_linter__rules__pygrep_hooks__tests__PGH002_PGH002_1.py.snap

@@ -15,6 +15,15 @@ PGH002_1.py:5:1: PGH002 `warn` is deprecated in favor of `warning`
 4 | logging.warn("this is not ok")
 5 | warn("not ok")
   | ^^^^ PGH002
+6 | 
+7 | logger = logging.getLogger(__name__)
+  |
+
+PGH002_1.py:8:1: PGH002 `warn` is deprecated in favor of `warning`
+  |
+7 | logger = logging.getLogger(__name__)
+8 | logger.warn("this is not ok")
+  | ^^^^^^^^^^^ PGH002
   |